During the fabrication of two different structures (a ship, a bridge) some unacceptable anomalies were detected; the structures were almost completely fabricated and a repair of the defected structural details was impractical, due to the extent of the defected zones. As far as the ship was concerned the anomalies were represented by a large number of welded joints, judged unacceptable according to the Design and Fabrication Code, while in the case of the bridge, the anomalies were represented by planar flaws in the plates forming the girder web, subjected to outof-plane loads for effect of fillet welded connections of bracing. A fitness for service assessment has therefore been carried out, in both cases, by performing fatigue tests on representative samples, cut-off from the structure, and by evaluating the fatigue resistance curve. A re-assessment of the structural details in question was undertaken, on the basis of the experimental S-N curve, evaluating the fitness for service of the “defected details”. The experimental program has also given the opportunity to compare different methodologies for fatigue assessment: the Effective Notch Stress Method, the Fracture Mechanics Method and the Peak Stress Method. The different procedures have been applied to the tested specimens, and the expected fatigue life was compared with the experimental one.
Fitness for service assessment of defected welded structural details by experimental evaluation of the fatigue resistance S-N curve
RIZZO, CESARE MARIO;
2014-01-01
Abstract
During the fabrication of two different structures (a ship, a bridge) some unacceptable anomalies were detected; the structures were almost completely fabricated and a repair of the defected structural details was impractical, due to the extent of the defected zones. As far as the ship was concerned the anomalies were represented by a large number of welded joints, judged unacceptable according to the Design and Fabrication Code, while in the case of the bridge, the anomalies were represented by planar flaws in the plates forming the girder web, subjected to outof-plane loads for effect of fillet welded connections of bracing. A fitness for service assessment has therefore been carried out, in both cases, by performing fatigue tests on representative samples, cut-off from the structure, and by evaluating the fatigue resistance curve. A re-assessment of the structural details in question was undertaken, on the basis of the experimental S-N curve, evaluating the fitness for service of the “defected details”. The experimental program has also given the opportunity to compare different methodologies for fatigue assessment: the Effective Notch Stress Method, the Fracture Mechanics Method and the Peak Stress Method. The different procedures have been applied to the tested specimens, and the expected fatigue life was compared with the experimental one.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
